04sleeper
Founding Member
I'm not sure why it stops.blackcloud50 said:
I really didn't notice that it ever stopped but just accumulated more (faster) with the filter out. That is why I kept it out.
Oil Separator Tanks
- Thread starter vristang
- Start date
I really didn't notice that it ever stopped but just accumulated more (faster) with the filter out. That is why I kept it out.
I am with Kevin. The PCV valve and rubber lines are still the same size. The effective volume of the separator does not matter much at all (esp since it ends up being a restriction of sorts).
When I first set my separator up (with element), oil would accumulate (I dont get much anyhow). But then I started to notice that as the element clogged up, the air going through the separator would swirl around in the basin (the oil in the bottom was being swirled around the sides of the bowl - not ideal). Then the accumulation stopped. I could hardly blow through the element.
I am with Kevin all the way about modifying it. No matter how we modify this, it is better than nothing. And it still is working as a catch can with no element. I didnt need one to begin with, but I get a little bit of oil pooling that is now not making to the intake tract. Every bit helps.
When I first set my separator up (with element), oil would accumulate (I dont get much anyhow). But then I started to notice that as the element clogged up, the air going through the separator would swirl around in the basin (the oil in the bottom was being swirled around the sides of the bowl - not ideal). Then the accumulation stopped. I could hardly blow through the element.
I am with Kevin all the way about modifying it. No matter how we modify this, it is better than nothing. And it still is working as a catch can with no element. I didnt need one to begin with, but I get a little bit of oil pooling that is now not making to the intake tract. Every bit helps.
352Ford2
New Member
HISSIN50 said:
Bigger the can the bigger the pressure drop, its just fluid mechanics. Same with increasing the length of the line, then you have a larger line drop.
think of it this way if you had a really long drinking straw, do you think you could sit on the top of a 3 story building and suck the water out of the swimming pool below?
I bet not
Not sure I follow the analogy. Overcoming the gravity to suck the water up 3 stories would be more significant to me than the flow rate (absent gravity).352Ford2 said:
Think of it this way. A cat converter is a larger diameter housing than the rest of the exhaust piping (2 1/4" or what have you). But there is not a pressure drop in the cat itself.
There might be a slight lag that occurs while initially filling the catch can (additional volume, not unlike additional volume from running longer lines) but once it is up to speed, it wont matter. The restriction in the separator is what comes into play more than the volume IMHO. Fluid dynamics again.
I think it is all moot. The PCV's active nature (actively sucking crankcase vapor out) is still leagues better than relying on breathers to passively vent excessive pressure. So in the scheme of things, once again it doesnt matter if there even is some small pressure drop (I might have to go put a gauge on things to put this argument to bed - I postulate no meaningful vacuum reading delta with the separator vs without). And the gains from not having oilly air make it into the intake and possibly chambers has some meaningful benefit IMHO. No matter who is right, this is a compromise I am willing to take (if there is any meaningful comromise in the first place).
352Ford2
New Member
HISSIN50 said:
pressure is directly related to crosssectional area, if you go from 2" to 2.5 to 2" pipe, you will have the lowest pressure at the end of the last 2" pipe (pressure drop) highest pressure will be in the 2.5" pipe
go here at the bottom of the page is a anamation of Bernoulis Principle
it doesn't do a good modle of line drop, but it's still kinda neat.
http://home.earthlink.net/~mmc1919/venturi.html
Apparently we dont see eachother's points, so we will have to let this one go.352Ford2 said:
I am considering dynamics like streamlined flow, which I dont see being considered otherwise.
I still stand by my point that it makes no real world difference - probably because I have run each configuration. And running a large can is nothing new.
Some good points.
My thought - If large volume separators reduced vac signal, then there would not be 1.5qt separators in use by so many race teams. The separators we are using are actually quite small.
However, I think the major influence on the ability of the pcv to work is the engine vac itself. The fact that there is no vac at wot and plenty of vac at idle bothers me. There is no vac signal when it is needed most, and plenty of vac when a vac signal is nearly useless. I realize that the pcv functions on the pressure differential between the crankcase and the intake, but this seems far from ideal to me.
That is why I put the air pump on the crankcase.
It seems to be working well, as I have not had the large plumes of smoke when I floor it. The thing that made the biggest difference was adding the filter material to the small Home Depot oil separator.
Still left to try...
I picked up one of the large Home Depot separators today. If it is not raining tomorrow (there is a slim to no chance of clear skies here in Seattle) I will install it in place of the smaller unit.
If that does not filter oil out of the crankcase gasses I will add some filter material to it. (I am not sure how the vac signal has been affected by the filter material, but I look forward to checking for a difference)
If that does not work (but I have no reason to think that it won't) I will add the small separator in line with the the large one.
Once I have proven that the air pump and separator can remove all of the oil from the crankcase gasses, I will route the exhaust of the air pump to the intake at the air filter. End result - better performance, better emissions, and possibly better economy.
I will post the finished product, if an interest is expressed.
Thanks for the great discussion,
jason
My thought - If large volume separators reduced vac signal, then there would not be 1.5qt separators in use by so many race teams. The separators we are using are actually quite small.
However, I think the major influence on the ability of the pcv to work is the engine vac itself. The fact that there is no vac at wot and plenty of vac at idle bothers me. There is no vac signal when it is needed most, and plenty of vac when a vac signal is nearly useless. I realize that the pcv functions on the pressure differential between the crankcase and the intake, but this seems far from ideal to me.
That is why I put the air pump on the crankcase.
It seems to be working well, as I have not had the large plumes of smoke when I floor it. The thing that made the biggest difference was adding the filter material to the small Home Depot oil separator.
Still left to try...
I picked up one of the large Home Depot separators today. If it is not raining tomorrow (there is a slim to no chance of clear skies here in Seattle) I will install it in place of the smaller unit.
If that does not filter oil out of the crankcase gasses I will add some filter material to it. (I am not sure how the vac signal has been affected by the filter material, but I look forward to checking for a difference)
If that does not work (but I have no reason to think that it won't) I will add the small separator in line with the the large one.
Once I have proven that the air pump and separator can remove all of the oil from the crankcase gasses, I will route the exhaust of the air pump to the intake at the air filter. End result - better performance, better emissions, and possibly better economy.
I will post the finished product, if an interest is expressed.
Thanks for the great discussion,
jason
352Ford2
New Member
vristang said:
Aren't those large volume separators for race teams used at the end of the vacuum source (like the vacuum pump would act like a pcv but pukes into the separator)?? This meaning that the separator is just a catch can really. Whereas the separator/catch can that would be inline between the pcv and upper is actually separating the aerated oil and not just used as a "puke can"
As far as the lack of pcv vacuum WOT vs. that under other driving conditions, that's one reason why there is a line running from the valve cover to the throttle body or inlet side of blower. Atleast that's my understanding of it.
blackcloud50 said:
I am not sure what you mean by the vac pump acting as a pcv? Can you elaborate?
The pcv itself is just a one way valve, designed to prevent backfires from getting out of the intake, and blowing up the crankcase (and all of the flammables in it).
In any evac pump setup you need to place the separator in line before the pump to prevent excess oil from getting to the pump. A "puke tank" does the same thing as our separators. It captures oil vapor in the incoming air, and lets it accumulate in the bottom of the can. The difference is that the inlet for the puke tanks is a much better design than what you will find at Home Depot.
I have heard this theory on why the tb/vc line is there. The theroy is that when the vac signal is weak the tb/vc line allows the crankcase pressure to vent. I am not sure I fully agree with this, and here's why.
I have had sufficient pressure build in the crankcase to blow the dipstick out of its tube (and by this I mean the dipstick hit the underside of the hood, and oil sprayed out of the tube). I have also had sufficient pressure build to blow out the rear seal on the lower intake. These 2 paths for crankcase pressure to vent are very high resistance paths compared to the resistance of the tb/vc line.
If venting crankcase pressure is a function of the tb/vc line, then it is a very poor design. As far as I can tell the tb/vc line is the inlet for fresh air entering the crankcase, and that is all it does.
I would love to hear others feed back on this.
jason
04sleeper
Founding Member
Yes. I am interested as well. If you don't mind.HISSIN50 said:Jason, you know I am interested in these things.(if you dont post results, please shoot me a PM or email).
What about something like this?
http://www.seanhylandmotorsport.com...=1054&osCsid=ac08e6f94b35869ab85c11311d195674
It's a bit pricey but people have reported good results with it on SC Cobras like mine.
I may try one on the passenger side VC along with the seperator on the drivers side.
vristang said:
What I meant was that the vacuum pump takes the place of the pcv (meaning its job is to evacuate the crankcase)
Are you saying that you were blowing the dipstick, rear main, and lower intake on an n/a motor? I was under the impression that the the air that was rushing through the throttle body into the motor under WOT would draw (pull some vacuum) on the "zip tube" that normally runs from the valve cover to the t/b. Or inlet side of blower if supercharged.
Quick question for anyone..If the tube on the throttle body (where the hose connects from the valve cover) was removed and left open, would air be coming out of the t/b or be drawn in?
if we look at the fitting on the oil filler, rather than the TB, the answer is Both. THat smaller line does have a secondary benefit for allowing crankcase vapor to vent at WOT. However, its primary purpose is to work in concert with the primary line, since PCV flow is bi-directional. WIthout that smaller line, one could draw a vacuum in the crankcase and air would try and find its way into the motor through the seals (this smaller line is what allows the bi-directional flow to occur).blackcloud50 said:
To answer your question further, if you left that small line like that on a MAF car, you would be ingesting unmetered air (this is why the PCV system is closed and that small line is placed past the MAF sensor).
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